Circular stapler with frictional reducing member

ABSTRACT

A circular stapling instrument is provided which includes a reciprocating drive shaft and a firing bar. The reciprocating drive shaft has a first engagement member at a tip of the reciprocating drive shaft and a threaded adjustment member at a base of the reciprocating drive shaft. The firing bar is movably connected at a first end with a firing trigger and movably connected at a second end with a stapling head assembly through a second engagement member. The firing bar forms a first engagement surface which faces a respective second engagement surface formed on the reciprocating drive shaft. The circular stapling instrument also includes a frictional reducing member located in between the first and second engagement surfaces in order to reduce friction between the reciprocating drive shaft and the firing bar.

FIELD OF THE DISCLOSURE

The present invention relates generally to circular staplers and, moreparticularly, to a circular stapling instrument having a frictionalreducing member for providing reduced friction between the firing barand a reciprocating drive shaft.

BACKGROUND OF THE DISCLOSURE

Circular stapling instruments are well known in the surgical art forbowel surgery. An example of such a device is the Endopath ILS ECS 25Endoscopic Curved Intraluminal Stapler made by Ethicon Endo Surgery Inc.Many circular stapler patents exist, for example U.S. Pat. No. 4,207,898to Becht, U.S. Pat. No. 4,351,466 to Noiles, U.S. Pat. No. 5,292,053 toBilotti et al., and U.S. Pat. 5,344,059 to Green et. al.

Currently, many circular stapling instruments employ a design whichincludes a movable reciprocating drive shaft for adjusting a distancebetween an anvil assembly and a stapling head assembly and a movablefiring bar for engaging the stapling head assembly and firing staplesfrom the stapling head assembly. Both the reciprocating drive shaft andthe firing bar slidably engage each other. Therefore, movement betweenthe reciprocating drive shaft and the firing bar results in frictionbetween the reciprocating drive shaft and the firing bar. Sometimes thefriction between the reciprocating drive shaft and the firing bar is sohigh that movement of either the reciprocating drive shaft or the firingbar is deterred or prevented, rendering the circular stapling instrumentat least partially inoperable. This is even more relevant in a curvedcircular stapling instrument wherein the instrument is reusable.Friction can be mitigated in disposable circular stapling instruments byutilizing polymeric materials for components requiring a lowercoefficient of friction, or by utilizing lubricants. However, inreusable circular stapling instruments the components are preferablymetallic due to the anticipated wear experienced during reuse.Friction-reducing lubricants, if used, will be removed during subsequentcleaning and sterilization steps. Current curved reusable circularstapling instruments do not operate effectively due to increasedfriction after lubricants wash out after a few reuses, and are a sourceof malfunction.

As a result it would be desirable to reduce the friction between thereciprocating drive shaft and the firing bar within a circular staplinginstrument.

SUMMARY

The present disclosure is defined by the claims, and nothing in thissection should be taken as a limitation on those claims.

In one aspect, a circular stapling instrument is provided. The circularstapling instrument includes a reciprocating drive shaft and a firingbar. The reciprocating drive shaft has a first engagement member at atip of the reciprocating drive shaft and a threaded adjustment member ata base of the reciprocating drive shaft. The firing bar is movablyconnected at a first end with a firing trigger and movably connected ata second end with a stapling head assembly through a second engagementmember. The firing bar forms a first engagement surface which faces arespective second engagement surface formed on the reciprocating driveshaft. The circular stapling instrument also includes a frictionalreducing member located in between the first and second engagementsurfaces in order to reduce friction between the reciprocating driveshaft and the firing bar.

In another aspect, a circular stapling instrument is provided. Thecircular stapling instrument includes a reciprocating drive shaft, afiring bar, and a frictional reducing member. The reciprocating driveshaft is for adjusting a distance between an anvil assembly and astapling head assembly. The firing bar is for engaging and activatingthe stapling head assembly to release staples. The firing bar forms afirst engagement surface which faces a respective second engagementsurface formed on the reciprocating drive shaft. The frictional reducingmember is located in between the first and second engagement surfaces inorder to reduce friction between the reciprocating drive shaft and thefiring bar.

In an additional aspect, a circular stapling instrument is provided. Thecircular stapling instrument includes a reciprocating drive shaft whichslidably engages a firing bar. The firing bar forms a first engagementsurface which faces a respective second engagement surface formed on thereciprocating drive shaft. The circular stapling instrument alsoincludes a frictional reducing member located in between the first andsecond engagement surfaces in order to reduce friction between thereciprocating drive shaft and the firing bar.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the disclosure.

FIG. 1 illustrates a perspective view of a reusable circular staplinginstrument having an open assembly architecture, in accordance with onepreferred embodiment;

FIG. 2 illustrates a perspective view of the reusable circular staplinginstrument of FIG.1 with the instrument in the open position with ananvil assembly separated from the remainder of the reusable circularstapling instrument;

FIG. 3 illustrates an exploded perspective view of a handle and shaftassembly of the reusable circular stapling instrument of FIG. 1;

FIG. 3A illustrates a cross-sectional view through line 3A-3A of aportion of a reciprocating anvil adjusting rod of the reusable circularstapling instrument of FIG. 3;

FIG. 3B illustrates a cross-sectional view through line 3B-3B of anotherportion of the reciprocating anvil adjusting rod of the reusablecircular stapling instrument of FIG. 3;

FIG. 4 illustrates an exploded perspective view of a stapling reloadassembly of the reusable circular stapling instrument of FIG. 1;

FIG. 5 illustrates a partial cross-sectional view through a staplingreload assembly of the reusable circular stapling instrument of FIG. 1in an unassembled configuration;

FIG. 6 illustrates a cross-section view through a stapling reloadassembly of the reusable circular stapling instrument of FIG. 1 in anassembled configuration with an anvil assembly in an open position andan annular blade in a pre-fired position;

FIG. 7 illustrates the view of FIG. 6 with the anvil assembly moved to aclosed position and with the annular blade still being in the pre-firedposition;

FIG. 8 illustrates an exploded perspective view of the anvil assembly ofthe reusable circular stapling instrument of FIG. 1;

FIG. 9 illustrates a flowchart of one embodiment of a method of aligninga stapling reload assembly of a circular stapling instrument;

FIG. 10 illustrates an exploded perspective view of another embodimentof an anvil assembly;

FIG. 11 illustrates a perspective view of the reusable circular staplinginstrument of FIG.1 replacing the anvil assembly with the anvil assemblyof FIG. 10 separated from the remainder of the reusable circularstapling instrument;

FIG. 12 illustrates an exploded perspective view of an additionalembodiment of an anvil assembly;

FIG. 13 illustrates a perspective view of the reusable circular staplinginstrument of FIG. 1 replacing the anvil assembly with the anvilassembly of FIG. 12 separated from the remainder of the reusablecircular stapling instrument;

FIG. 14 illustrate a flowchart showing one embodiment of a method ofmanufacturing an anvil assembly;

FIGS. 15A and 15B illustrate perspective assembly views, duringdifferent stages of assembly, of an anvil closure knob and areciprocating anvil adjusting rod of the reusable circular staplinginstrument of FIG. 1;

FIGS. 16A and 16B illustrate perspective assembly views, duringdifferent stages of assembly, of the anvil closure knob connected withthe reciprocating anvil adjusting rod of FIGS. 15A and 15B along with ahandle of the reusable circular stapling instrument of FIG. 1;

FIGS. 17A, 17B and 17C illustrate perspective assembly views, duringdifferent stages of assembly, of the anvil closure knob connected withthe reciprocating anvil adjusting rod and the handle of FIGS. 16A and16B along with a firing bar of the reusable circular stapling instrumentof FIG. 1;

FIGS. 18A and 18B illustrate perspective assembly views, duringdifferent stages of assembly, of the anvil closure knob connected withthe reciprocating anvil adjusting rod , the handle, and the firing barof FIGS. 17A, 17B, and 17C along with a carrier cover of the reusablecircular stapling instrument of FIG. 1;

FIGS. 19A, 19B and 19C illustrate perspective assembly views, duringdifferent stages of assembly, of the anvil closure knob connected withthe reciprocating anvil adjusting rod , the handle, the firing bar, andthe carrier cover of FIGS. 18A, and 18B along with a shaft assembly ofthe reusable circular stapling instrument of FIG. 1;

FIG. 20 illustrates a perspective view of a curved reusable circularstapling instrument having an open assembly architecture, in accordancewith another preferred embodiment;

FIG. 21 illustrates an exploded perspective view of the curved reusablecircular stapling instrument of FIG. 20;

FIG. 22 illustrates a cross-section view of a curved circular staplinginstrument having a frictional reducing member, with the instrument inan open condition;

FIG. 23 illustrates a curved cross-section view of a circular staplinginstrument having a frictional reducing member, with the instrument in aclosed position before firing staples;

FIG. 24 illustrates a cross-section view of a curved circular staplinginstrument having a frictional reducing member, with the instrument in afully fired condition upon firing staples;

FIG. 25 illustrates a perspective view of a firing bar of a curvedcircular stapling instrument having a frictional reducing member;

FIG. 26 illustrates an exploded perspective view of a firing bar of acircular stapling instrument having a frictional reducing member;

FIG. 27 illustrates a cross-section view of a firing bar of a circularstapling instrument having a frictional reducing member;

FIG. 28 illustrates an enlarged side view of a firing bar of a circularstapling instrument having an alternate embodiment of a frictionalreducing member adjacent a reciprocating anvil adjusting rod;

FIG. 29 illustrates a cross-section view of an annular blade of thestapling reload assembly of the circular stapling instrument of FIG. 4;

FIG. 30 illustrates a perspective view of an annular breakaway washerattached to a protective member;

FIG. 31 illustrates the view of FIG. 7 with the annular blade moved tothe fired position cutting an annular breakaway washer while the anvilassembly is in the closed position;

FIG. 32 illustrates a close-up view, within the dotted circle of theannular blade of FIG. 31, showing the annular blade cutting the annularbreakaway washer;

FIG. 33 illustrates the view of FIG. 31 with the anvil assembly havingbeen moved back into the open position after the annular blade wasfired;

FIG. 33A illustrates a close-up side view of one embodiment of an anvilcontrol member connected to a handle of a reusable circular staplinginstrument;

FIG. 34 illustrates the view of FIG. 33 with an anvil of the anvilassembly removed from the circular stapling instrument and the annularbreakaway washer and a protective member attached to the annular blade;

FIG. 35 illustrates the view of FIG. 34 with a new anvil having beenattempted to be attached to the stapling reload assembly and theprotective member and the annular breakaway washer interfering with theattachment;

FIG. 36 illustrates a close-up view within the dotted circle of FIG. 35showing the protective member and the annular breakaway washerinterfering with the attachment of the new anvil to the stapling reloadassembly;

FIG. 37 illustrates a flowchart of one embodiment of a method of lockinga blade to a breakaway washer of a circular stapling instrument;

FIG. 38 illustrates a cross-sectional view through the reusable circularstapling instrument of FIG. 1 with the anvil assembly disposed in anopen position, out of a firing zone, away from a casing with a firingtrigger in a locked, pre-fired state;

FIG. 38B illustrates a close-up view showing the relationship between afiring trigger and the firing bar in the assembled condition of FIG.17C;

FIG. 39 illustrates a partial perspective view of the cross-sectionalview of FIG. 38;

FIG. 40 illustrates a cross-sectional view through line 40-40 of FIG.38;

FIG. 41 illustrates a cross-sectional view through the reusable circularstapling instrument of FIG. 1 with the anvil assembly disposed in aclosed position, in the firing zone, adjacent the casing with the firingtrigger in an unlocked, pre-fired state ready to fire;

FIG. 42 illustrates a partial perspective cross-sectional view of FIG.41;

FIG. 43 illustrates a cross-sectional view through line 43-43 of FIG.41;

FIG. 44 illustrates a cross-sectional view through the reusable circularstapling instrument of FIG. 1 with the anvil assembly disposed in theclosed position, in the firing range, adjacent the casing with thefiring trigger having been fired;

FIG. 45 illustrates a partial perspective view of the cross-sectionalview of FIG. 44;

FIG. 46 illustrates a cross-sectional view through line 46-46 of FIGS.44; and

FIGS. 47A and 47B illustrate cross-sectional views of a stapling reloadassembly in an attached state to a handle, with an anvil in open andclosed conditions respectively.

DETAILED DESCRIPTION

With reference to FIG. 1, there is shown a novel surgical circularstapling instrument 100 for the removal of tissue from a human patientconsistent with the present disclosure. The surgical circular staplinginstrument 100 may be used to remove tissue comprising internalhemorrhoids, or other types of human tissue. The circular staplinginstrument 100 has been adapted from a conventional circular staplinginstrument, as shown in U.S. Pat. No. 6,102,271, the contents of whichare incorporated by reference herein in their entirety. The circularstapling instrument 100 has a stapling reload assembly 102 adapted toplace an annular array of staples 104 (see FIGS. 7 and 31) into amucosal layer at the base of internal hemorrhoids and to cut the mucosaltissue along with the internal hemorrhoids from the inside wall of arectum or anus. In general, circular stapling instrument 100 may be usedto anastomose two sections of bowel together with an annular ring of thestaples 104 (see FIGS. 7 and 31) while cutting a plug from a center ofan annular formed staple ring for the passage of fecal material.

With reference to FIGS. 1-2, circular stapling instrument 100 includesan ergonomic shaft assembly 106, a stapling cartridge assembly 108having a casing 110, and an anvil assembly 112 detachably connected to areciprocating anvil adjusting rod 114. The stapling reload assembly 102of the circular stapling instrument includes the stapling cartridgeassembly 108 and the anvil assembly 112. As shown in FIGS. 1-3, thecircular stapling instrument 100 further includes a handle 116 forming acavity 118. An anvil control member 120 is located on the proximal endof the handle 116 and is operatively coupled with the anvil assembly 112such that rotation of the anvil control member 120 moves the anvilassembly 112 proximally or distally, depending on the direction ofrotation of the anvil control member 120. The anvil control member 120may comprise an anvil closure knob or other type of anvil controlmember. The circular stapling instrument 100 includes a firing trigger122 which is rotate-able in direction 124 from the open position shownto a closed position in which the staples 104 (see FIGS. 7 and 31) areinjected into tissue (see FIG. 31) and excess tissue is cut with anannular blade 126 (see FIG. 31) of the stapling reload assembly 102. Asafety latch 128 is located on the firing trigger 122 and is shown in anup and engaged position which prevents operation of the firing trigger122. When the safety latch 128 is disengaged and moved inwards anddownwards in direction 128 a, the firing trigger 122 is free to rotatein direction 124 from the open position to the closed position. Theshaft assembly 106 extends distally from the handle 116 and detachablycouples with the handle 116 at a proximal end using a connecting nut 130that attaches to a threaded portion 132 (see FIG. 3) of handle 116.Opposed attachment members 134 (see FIG. 4) of the casing 110 detachablycouple to receiving members 136 (see FIG. 3) at a distal end of theshaft assembly 106. The attachment members 134 comprise deflectable snapmembers and the receiving members 136 comprise apertures. In otherembodiments, the attachment members 134 and the receiving members 136may comprise any type of mating members.

As shown in FIG. 2, the casing 110 has an exterior surface 138 having aflared driver portion 140 and an outer tubular driver portion 142.Passageways 144 comprise a casing surface aperture extending from theflared driver portion 140 to the outer tubular driver portion 142. Anannular staple holder 148 (see FIGS. 4-5, 7, and 31) is attached withina distal end of the casing 110 with attachment members 150 (see FIGS. 4,7, and 31) of the staple holder 148 detachably connected to receivingmembers 152 (see FIGS. 4, 7, and 31) of the casing 110. The attachmentmembers 150 comprise snap projections and the receiving members 152comprise deflectable snaps. In other embodiments, the attachment members150 and the receiving members 152 may each comprise any type ofconnectable members. The annular staple holder 148 includes an annulararray of staple slots 154 (see FIGS. 4, 7, and 31) for holding andemitting the staples 104 (see FIG. 31).

As shown in FIGS. 4-7, a staple driver 156 slidably connects to theannular staple holder 148 with keys 158 (see FIG. 4) of the stapledriver 156 providing an arrangement that is a detachable connection tokeyways 160 (see FIG. 4) of the annular staple holder 148. The stapledriver 156 movably mounts within the casing 110 with alignment slots 162of an annular exterior driver surface 164 of the staple driver 156moveably connected to alignment splines 166 of an annular interiorcasing surface 168 of the casing 110 allowing longitudinal movement ofthe staple driver 156 within the casing 110 while preventing rotation ofthe staple driver 156 within the casing 110. The exterior driver surface164 of the staple driver 156 has a flared driver portion 170 and anouter tubular driver portion 171. The alignment slots 162 and alignmentsplines 166 are disposed parallel to longitudinal axis 172 and 174 ofthe staple driver 156 and the casing 110. In other embodiments, thecasing 110 and staple driver 156 may be aligned relative to one anotherusing any number, type, or configuration of alignment members whichallow longitudinal movement.

The staple driver 156 has a plurality of fingers 176 that are receivedwithin the staple slots 154 within the staple holder 148. The fingers176 are for engaging and driving a plurality of the staples 104 (seeFIG. 31) from the staple slots 154 of the staple holder 148 as thestaple driver 156 is moved from a pre-fired position (see FIG. 7) to afired position (see FIG. 31) by actuation of the firing trigger 122 (seeFIG. 3). As shown in FIGS. 4 and 7, flexible detent members 178 of thestaple driver 156 are detachably connected to detent bumps 180 of thecasing 110. This arrangement allows longitudinal movement of the stapledriver 156 only when a predetermined amount of force is exerted by afiring bar 282 (see FIGS. 44-46) on the staple driver 156. When therequired force is exerted the deflectable detent members 178 on thestaple driver 156 bend inwards thereby disengaging from the detent bumps180 on the casing 110 allowing the staple driver 156 to movelongitudinally and distally. In other embodiments, the flexible detentmember 178 and the detent bumps 180 may comprise other types of matingmembers.

The annular blade 126 is mounted within the distal end of the stapledriver 156 and is attached by a plurality of blade mounting pins 182(see FIGS. 5 and 31) that project through a like number of mountingholes 184 within a base 186 of the annular blade 126. The annular blade126 has a blade opening 188 (see FIGS. 5 and 31) within the base 186.The open distal end 190 (see FIGS. 4, 29, and 31) of the annular blade126 has a cutting edge 192. The annular blade 126 moves with the stapledriver 156 when the staple driver 156 is moved distally from thepre-fired position of FIG. 7 to the fired position of FIG. 31 using thefiring trigger 122 (see FIG. 3). When the firing trigger 122 is fired,the firing trigger 122 rotates in direction 124 from its position ofFIGS. 38-43 to its position of FIGS. 44-46 forcing a mated firing bar282 within the casing 110 to move in direction 392 abutting against andforcing the staple striver 156 to also move within the casing 110 indirection 392. This movement fires the staple driver 156, and itsattached annular blade 126, from its pre-fired position of FIGS. 7 and38-43 to its fired position of FIGS. 31 and 44-46. During the firing ofthe staple driver 156, the fingers 176 of the staple driver 156 fire thestaples 104 from their pre-fired position in the staple holder 148 shownin FIG. 7 to their fired position out of the staple holder 148 shown inFIG. 31.

The reciprocating anvil adjusting rod 114 (see FIGS. 4 and 6) is locatedwithin the stapling cartridge assembly 108 and is positioned to extendthrough and move within an annular interior shaft 194 (see FIGS. 4 and6) of the staple driver 156. As shown in FIGS. 3A and 3B, thecross-section of the reciprocating anvil adjusting rod 114 varies inshape and size with one portion along cross-sectional line 3A-3A beingof circular shape and having a diameter 401 as shown in FIG. 3A, andanother portion along cross-sectional line 3B-3B having parallelside-walls spaced apart by a distance 402, smaller than diameter 401, asshown in FIG. 3B. As shown in FIG. 4, the annular interior shaft 194extends longitudinally within the staple driver 156 parallel to thelongitudinal axis 172 of the staple driver 156. A hole 196 extendswithin the annular interior shaft 194. An anvil alignment surface 198extends longitudinally along an annular interior surface 200 of theannular interior shaft 194. The anvil alignment surface 198 comprises atleast one longitudinal slot. In other embodiments, the anvil alignmentsurface 198 may comprise any number or type of alignment surfaces invarying configurations. An exterior surface 204 of the annular interiorshaft 194 is spaced apart from another annular interior surface 206 ofthe staple driver 156 with an annular hole 208 extending between theexterior surface 204 of the annular interior shaft 194 and the annularinterior surface 206.

With reference to FIGS. 1, 2, 4-7, and in particular FIG. 8 the anvilassembly 112 comprises an anvil 210, a staple forming surface 212, anannular breakaway washer 214, and a metal shaft 216. The anvil 210 is aone-piece polymeric molded part comprising an anvil shaft 218 integrallymolded to an anvil base surface 220. The anvil 210 is made of a polymercomprising glass filled or carbon filled Nylon. In other embodiments,the anvil 210 may be made of similar composite materials having atensile strength greater than 15,000 psi in order to prevent excessivebending under tissue forces.

The anvil base surface 220 is molded to the staple forming surface 212and metal shaft 216. In other embodiments, the anvil base surface 220may be attached to the staple forming surface 212 using varyingattachment mechanisms. The staple forming surface 212 is made of sheetmetal or a plate comprising stainless steel, is annular in shape, andincludes staple forming pockets. In other embodiments, the stapleforming surface 212 may be made of Aluminum or other materials that canwithstand staple forming forces.

The annular breakaway washer 214 is press-fit within a cavity 222 of theanvil base surface 220 adjacent to the anvil base surface 220. In otherembodiments, the annular breakaway washer 214 may be attached within thecavity 222 of the anvil base surface 220 using varying attachmentmechanisms. The annular breakaway washer 214 is made of a plasticcomprising ABS (Acrylonotrile-Butadiene-Styrene). In other embodiments,the annular breakaway washer 214 may be made of Nylon, Polyethylene orPolypropylene.

The anvil shaft 218 is molded around an exterior surface 224 of an end226 of the metal shaft 216, with the metal shaft 216 extending into amolded hole 228 of the anvil shaft 218. The molded hole 228 of the anvilshaft 218 ends within the anvil shaft 218 and does not extend throughthe distal end of the anvil base surface 220. An interior surface 230 ofthe anvil shaft 218 comprises receiving members 232 which are molded toattachment members 234 of the exterior surface 224 of the end 226 of themetal shaft 216. The receiving members 232 comprise molded annular ribs(FIG. 38), and the attachment members 234 comprise annular grooves (FIG.8). In other embodiments, the receiving members 232 and attachmentmembers 234 may comprise grooves and threads, female and male members,or other types of attachment mechanisms. In still other embodiments, theanvil shaft 218 may be attached to the metal shaft 216 using varyingattachment mechanisms. A proximal end channel 236 extends through themetal shaft 216. End 238 of the metal shaft 216 includes expansion slots240 (see FIG. 2). The metal shaft 216 is made of a stainless steel. Inother embodiments, the metal shaft 216 may be made of varying materials.

At the time of manufacture of the anvil assembly 112, the metal shaft216 and the staple forming surface 212 are pre-manufactured. Thepre-manufactured metal shaft 216 and the pre-manufactured staple formingsurface 212 are then inserted into an injection mold. The mold is thenused to form the anvil 210 within the mold causing the anvil 210 to bemolded to both the pre-manufactured metal shaft 216 and to thepre-manufactured staple forming surface 212. During the molding processthe anvil base surface 220 forms and is molded to the pre-manufacturedstaple forming surface 212, while the anvil shaft 218 forms and ismolded around the end 226 of the pre-machined metal shaft 216. Theannular breakaway washer 214 is then press-fit within the cavity 222 ofthe molded anvil base surface 220. In other embodiments, themanufacturing process may vary.

The engagement member 244 (see FIGS. 2 and 6) of the reciprocating anviladjusting rod 114 detachably couples within the proximal end channel 236of the metal shaft 216 using a snap-fit coupling. This arrangementoperatively couples the metal shaft 216 and the attached anvil 210 tothe anvil control member 120 of the reciprocating anvil adjusting rod114. In other embodiments, the engagement member 244 of thereciprocating anvil adjusting rod 114 may be attached to the metal shaft216 using other attachment mechanisms. The expansion slots 240 allow end238 of the metal shaft 216 to expand during the coupling to theengagement member 244 of the reciprocating anvil adjusting rod 114.After using the circular stapling instrument 100 on a patient, theentire anvil assembly 112 is disposed of. During a subsequent procedure,a new stapling reload assembly 102, which includes a new anvil assembly112, is used.

As shown in FIG. 8, the anvil shaft 218 includes an alignment surface246 formed at the time of molding the anvil 210. The alignment surface246 comprises at least one spline disposed parallel to a longitudinalaxis 248 of the anvil shaft 218. The alignment surface 246 extends froma top portion 250 of the anvil shaft 218, along an exterior annularsurface 252 of the anvil shaft 218, to a bottom portion 254 of the anvilshaft 218. The metal shaft 216 of the anvil assembly 112 does notcontain an alignment surface. In other embodiments, the alignmentsurface 246 may comprise any number or type of alignment surfaces invarying configurations. For instance, as shown in FIG. 12, in anembodiment in which the anvil assembly 112 only includes the anvil shaft218 without the metal shaft 216 being attached to the anvil assembly112, the alignment surface 246 may extend from a top portion 250 of theanvil shaft 218, along the exterior annular surface 252 of the anvilshaft 218, and stop at a middle portion 256 of the anvil shaft 218without extending to the bottom portion 254 of the anvil shaft 218.

The anvil assembly 112 is movable from an open position (see FIG. 6) inwhich the staple forming surface 212 is disposed away from the casing110 for the reception of tissue, to a closed position (see FIG. 7) inwhich the staple forming surface 212 is disposed adjacent to the casing110 of the stapling cartridge assembly 108 clamping tissue between thestaple holder 148 and the staple forming surface 212 prior to firing thestaple driver 156 to staple and cut the clamped tissue. This is due tothe tip 242 (see FIGS. 2 and 6) of the engagement member 244 of thereciprocating anvil adjusting rod 114 extending within the annularinterior shaft 194 of the staple driver 156 and being connected withinthe channel 236 of proximal end 238 of the metal shaft 216 of the anvilassembly 112. As a result, due to movement of the connectedreciprocating anvil adjusting rod 114, the anvil shaft 218, which isconnected to the metal shaft 216, is moveably disposed within theannular interior shaft 194 of the staple driver 156 allowing movement ofthe staple forming surface 212 of the anvil assembly 112 relative to thestaple driver 156 and casing 110.

The alignment surface 246 (see FIG. 8) of the anvil shaft 218 isconfigured to mate with the anvil alignment surface 198 (see FIG. 4) ofthe staple driver 156 to rotationally align the staple forming surface212 with the staple holder 148 when the anvil base surface 220 is in theclosed position (see FIG. 7) adjacent to the stapling cartridge assembly108. Initially, as shown in FIG. 6, as the reciprocating anvil adjustingrod 114 moves the metal shaft 216 and the attached anvil shaft 218,thereby moving the anvil base surface 220 from the open position shownin FIG. 6 towards the closed position shown in FIG. 7, the alignmentsurface 246 (see FIG. 8) of the anvil shaft 218 is not mated with theanvil alignment surface 198 (see FIG. 4) of the annular interior shaft194 of the staple driver 156 because the anvil alignment surface 198will only be disposed adjacent to the metal shaft 216 which lacks analignment surface. During this time, the staple forming surface 212 willnot be rotationally aligned with the staple holder 148. However, asshown in FIG. 7, when the alignment surface 246 of the anvil shaft 218reaches the annular interior shaft 194 of the staple driver 156, thealignment surface 246 will mate with the anvil alignment surface 198 ofthe annular interior shaft 194 rotationally aligning the staple formingsurface 212 with the staple holder 148 as the anvil base surface 220moves into the closed position adjacent to the stapling cartridgeassembly 108. Referring to FIG. 33A, the markings 120A adjacent theanvil control member 120 visually indicate the gap distance between thestaple forming surface 212 of the anvil 112 (see FIG. 7) and the stapleguide 148 (see FIG. 7) providing feedback to the user on the compressedtissue thickness. When the device is near full closure the proximal endof the reciprocating anvil adjusting rod 114 pops through the hole 120Fin the anvil control member 120.

When the anvil assembly 112 is in the closed position of FIG. 7 and thecircular stapling instrument is fired 100, moving the staple driver 156from its pre-fired position within the casing 110 shown in FIG. 7 to itsfired position shown in FIG. 31, the fingers 176 of the staple driver156 drive the staples 104 from the staple slots 154 of the staple holder148 against the staple forming surface 212 of the anvil assembly 112.The staple forming surface 212 form the ejected staples 104 into aclosed staple shape thereby stapling portions of tissue together.Simultaneously, the staple driver 156 drives the annular blade 126 intothe compressed tissue captured between the staple forming surface 212 onthe anvil 210 and the surface of the staple guide 148, thereby cuttingthe tissue against the breakaway washer 214 of the anvil assembly 112.

FIG. 9 illustrates a flowchart 258 showing one embodiment of a method ofaligning a stapling reload assembly of a circular stapling instrument.In step 260, a stapling reload assembly of a circular staplinginstrument is provided. The provided circular stapling instrumentincludes a casing, a staple holder attached to the casing, a stapledriver, an annular blade, and an anvil. In step 262, the staple driveris movably mounted within the casing in an aligned configuration, andattachment members of the staple driver are connected to receivingmembers of the casing preventing the staple driver from moving past acertain point within the casing until a predetermined amount of force isapplied on the staple driver by a firing bar. In step 264, an anvil basesurface of the anvil is moved from an open position away from thecasing, in which a staple forming surface of the anvil is notrotationally aligned with the staple holder attached to the casing,towards a closed position adjacent to the casing. In step 266, analignment surface of the anvil is mated with an anvil alignment surfaceof the staple driver to rotationally align the staple forming surface ofthe anvil with the staple holder when the anvil base surface is in theclosed position adjacent to the casing. The alignment surface of theanvil comprises at least one spline, and the anvil alignment surface ofthe staple driver comprises at least one slot. In other embodiments, thenumber, type, and configuration of the alignment surface of the anviland the anvil alignment surface of the driver may vary.

One or more embodiments of the disclosure may reduce one or moreproblems associated with alignment in previous surgical circularstapling instruments. For instance, use of one or more embodiments ofthe disclosure may provide proper alignment directly between the anviland the staple driver instead of requiring a first alignment between theanvil and the casing, and a second alignment between the staple driverand the casing as is done in current devices. This method of directlyaligning the driver and the anvil reduces the potential of alignmentvariation and results in improved staple form.

FIG. 10 illustrates an exploded view of another embodiment of an anvilassembly 112A comprising an anvil 210A, a staple forming surface 212A,an annular breakaway washer 214A, and a metal shaft 216A. The anvil 210Ais a one-piece, polymer, molded part comprising an anvil shaft 218Amolded to an anvil base surface 220A. The anvil 210A is made of apolymer comprising glass filled or carbon filled Nylon. In otherembodiments, the anvil 210A may be made of similar composite materialshaving a tensile strength greater than 15,000 psi in order to preventexcessive bending under tissue forces.

The metal shaft 216A extends through a molded hole 228A which extendsthrough both the anvil shaft 218A and the anvil base surface 220A. Oneend 226A of the metal shaft 216A extends out of the molded hole 228A andabuts against a top portion 268 of the anvil base surface 220A. End 226Aof the metal shaft 216A has a larger diameter 270 than the diameter 272of the molded hole 228A. The other end 238A of the metal shaft 216Aextends out of the molded hole 228A of the anvil shaft 218A. The metalshaft 216A comprises attachment members (hidden from sight) which attachto receiving members (hidden from sight) of the anvil shaft 218A. Theattachment members comprise threads and the receiving members comprisegrooves. In other embodiments, the attachment members and receivingmembers may comprise male and female members, or other types ofattachment mechanisms. In still other embodiments, the metal shaft 216Amay be attached to the anvil shaft 218A using varying attachmentmechanisms. A channel 236A extends within proximal end 238A of the metalshaft 216A. End 238A of the metal shaft 216A also includes expansionslots 240A. The metal shaft 216A is made of a metal comprisingheat-treated stainless steel. In other embodiments, the metal shaft 216Amay be made of other steels.

The anvil base surface 220A is molded to the staple forming surface212A. In other embodiments, the anvil base surface 220A may be attachedto the staple forming surface 212A using varying attachment mechanisms.The staple forming surface 212A is made of a sheet metal comprisingaustenitic stainless steel, is annular in shape, and includes stapleforming pockets. In other embodiments, the staple forming surface 212Amay be made of other metals, stainless steels, Aluminum, sheet, orplate.

The annular breakaway washer 214A is press-fit within a cavity 222A ofthe anvil base surface 220A adjacent to the anvil base surface 220A. Inother embodiments, the annular breakaway washer 214A may be attachedwithin the cavity 222A of the anvil base surface 220A using varyingattachment mechanisms. The annular breakaway washer 214A is made of aplastic comprising ABS (Acrylonotrile-Butadiene-Styrene). In otherembodiments, the annular breakaway washer 214A may be made of Nylon,Polyethylene, or Polypropylene.

At the time of manufacture of the anvil assembly 112A, the stapleforming surface 212A is pre-manufactured. The pre-manufactured stapleforming surface 212A is then inserted into an injection mold. The moldis then used to form the anvil 210A within the mold causing the anvil210A to be molded to the staple forming surface 212A. During the moldingprocess the anvil base surface 220A forms and is molded to the stapleforming surface 212A. The annular breakaway washer 214A is thenpress-fit within the cavity 222A of the molded anvil base surface 220A.After molding the anvil base surface 220A, end 238A of apre-manufactured metal shaft 216A is extended into the molded hole 228Ain the anvil base surface 220A and out of the molded hole 228A in theanvil shaft 218A so that end 226A of the metal shaft 216A abuts againstthe top portion 268 of the anvil base surface 220A. This step can beperformed by the user prior to use. The metal shaft 216A is detachablyconnected to the anvil shaft 218A due to the attachment members (hiddenfrom view) of the metal shaft 216A mating with the receiving members(hidden from view) of the anvil shaft 218A as end 238A of thepre-manufactured metal shaft 216A is extended into and out of the moldedhole 228A in the anvil 210A. In other embodiments, the manufacturingprocess may vary.

As shown in FIG. 11, the engagement member 244 of the reciprocatinganvil adjusting rod 114 detachably couples within the proximal endchannel 236A of the metal shaft 216A using a snap-fit couplingoperatively coupling the metal shaft 216A and the attached anvil 210A tothe anvil control member 120 through the reciprocating anvil adjustingrod 114. In other embodiments, the engagement member 244 of thereciprocating anvil adjusting rod 114 may be attached to the metal shaft216A using other attachment mechanisms. The expansion slots 240A allowend 238A of the metal shaft 216A to expand during the coupling to theengagement member 244 of the reciprocating anvil adjusting rod 114.After using the circular stapling instrument 100 on a patient, the metalshaft 216A may be removed from the anvil 210A by detaching theattachment members (hidden from sight) of the metal shaft 216A from thereceiving members (hidden from sight) of the anvil shaft 218A, the anvil210A may be disposed of, the metal shaft 216A may be sterilized, and themetal shaft 216A may be attached to a new anvil using the sameabove-described process to allow the metal shaft 216A to be reused onanother patient in combination with the new anvil and new staplingcartridge assembly.

As shown in FIGS. 10-11, the anvil shaft 210A includes an alignmentsurface 246A formed at the time of molding the anvil 210A due to themold. The alignment surface 246A comprises at least one spline disposedparallel to a longitudinal axis 248A of the anvil shaft 218A. Thealignment surface 246A extends from a top portion 250A of the anvilshaft 218A, along an exterior annular surface 252A of the anvil shaft218A, to a bottom portion 254A of the anvil shaft 218A. The metal shaft216A of the anvil assembly 112A does not contain an alignment surface.In other embodiments, the alignment surface 246A may comprise any numberor type of alignment surfaces in varying configurations.

FIG. 12 illustrates an exploded view of another embodiment of an anvilassembly 112B comprising an anvil 210B, a staple forming surface 212B,and an annular breakaway washer 214B. The anvil 210B is a one-piece,polymer, molded part comprising an anvil shaft 218B molded to an anvilbase surface 220B. The anvil 210B is made of a polymer comprising glassfilled or carbon filled Nylon. In other embodiments, the anvil 210B maybe made of similar composite materials having a tensile strength greaterthan 15,000 psi in order to prevent excessive bending under tissueforces. A proximal end channel 236B extends within the anvil shaft 218B.Anvil shaft 218B includes expansion slots 240B.

The anvil base surface 220B is molded to the staple forming surface212B. In other embodiments, the anvil base surface 220B may be attachedto the staple forming surface 212B using varying attachment mechanisms.The staple forming surface 212B is made of a metal comprising austeniticstainless steel, is annular in shape, and includes staple formingpockets. In other embodiments, the staple forming surface 212B may bemade of other metals, stainless steels, Aluminum, sheet, or plate.

The annular breakaway washer 214B is press-fit within a cavity 222B ofthe anvil base surface 220B adjacent to the anvil base surface 220B. Inother embodiments, the annular breakaway washer 214B may be attachedwithin the cavity 222B of the anvil base surface 220B using varyingattachment mechanisms. The annular breakaway washer 214B is made of aplastic comprising ABS (Acrylonotrile-Butadiene-Styrene). In otherembodiments, the annular breakaway washer 214B may be made of varyingmaterials.

At the time of manufacture of the anvil assembly 112B, the stapleforming surface 212B is pre-manufactured. The pre-manufactured stapleforming surface 212B is then inserted into an injection mold. The moldis then used to form the anvil 210B within the mold causing the anvil210B to be molded to the staple forming surface 212B. During the moldingprocess the anvil base surface 220B forms and is molded to the stapleforming surface 212B. At the same time the anvil shaft 218B, includingthe anvil rod attachment portion, is integrally molded to the anvil basesurface 220B. The annular breakaway washer 214B is then press-fit withinthe cavity 222B of the molded anvil base surface 220B. In otherembodiments, the manufacturing process may vary.

As shown in FIG. 13, the engagement member 244 of the reciprocatinganvil adjusting rod 114 detachably couples within the proximal endchannel 236B of the anvil shaft 218B using a snap-fit couplingoperatively coupling the anvil shaft 218B of the anvil 210B to the anvilcontrol member 120 through the reciprocating anvil adjusting rod 114. Inother embodiments, the engagement member 244 of the reciprocating anviladjusting rod 114 may be attached to the anvil shaft 218B using otherattachment mechanisms. The expansion slots 240B allow the anvil shaft218B to expand during the coupling to the engagement member 244 of thereciprocating anvil adjusting rod 114. After using the circular staplinginstrument 100 on a patient, the anvil 210B may be disposed of, and anew anvil may be used with the circular stapling instrument 100 to doanother procedure on a different patient.

As shown in FIGS. 12-13, the anvil shaft 218B includes an alignmentsurface 246B formed at the time of molding the anvil 210B. The alignmentsurface 246B comprises at least one spline disposed parallel to alongitudinal axis 248B of the anvil shaft 218B. The alignment surface246B extends from a top portion 250B of the anvil shaft 218B, along anexterior annular surface 252B of the anvil shaft 218B, and stops at amiddle portion 256B of the anvil shaft 218A without extending to thebottom portion 254B of the anvil shaft 218A. In other embodiments, thealignment surface 246B may comprise any number or type of alignmentsurfaces in varying configurations.

FIG. 14 illustrates a flowchart 274 showing one embodiment of a methodof manufacturing an anvil assembly. In step 276, a pre-manufacturedstaple-forming surface, which may be made of metal or other material, isdisposed within a mold. In step 278, the anvil assembly is formed bymolding an anvil to the pre-manufactured staple-forming surface withinthe mold, with the anvil molded to have an anvil shaft extending from ananvil base surface. The anvil may be molded to be one-piece from apolymer such as glass filled or carbon filled Nylon. In otherembodiments, the anvil may be molded out of other materials. In oneembodiment, step 278 may further include molding the anvil shaft to haveat least one alignment surface comprising an alignment spline or anothertype of alignment surface. In another embodiment, step 278 may furtherinclude molding the anvil assembly so that the anvil shaft is molded toa pre-manufactured shaft, which may be made of metal or other materials,disposed within the mold during step 276. In an additional embodiment,in a subsequent step, a pre-manufactured shaft, which may be made ofmetal or other materials, may be attached to the anvil shaft of themolded anvil assembly after the anvil is molded. In step 280, abreakaway washer is attached, using press-fitting or other attachmentmechanisms, to the anvil base surface of the molded anvil assembly. Thebreakaway washer may be annular or in another shape, may be made of aplastic comprising ABS (Acrylonotrile-Butadiene-Styrene), or may be madeof other types of materials. In other embodiments, one or more steps ofthe method may vary.

One or more embodiments of the disclosure may reduce one or moreproblems associated with previous anvil assemblies. For instance, use ofone or more embodiments of the disclosure may provide an anvil assemblywhich may be manufactured at one-third the cost of current anvilassemblies.

As shown in FIGS. 1-3, the circular stapling instrument 100 includeshandle 116, reciprocating anvil adjusting rod 114, firing bar 282,carrier cover 284, shaft assembly 106 detachably coupled with the handle116, stapling cartridge assembly 108, and anvil assembly 112 which isdetachably coupled with the reciprocating anvil adjusting rod 114. Thehandle 116 forms a cavity 118 which receives the firing bar 282 and thereciprocating anvil adjusting rod 114. The reciprocating anvil adjustingrod 114 has an engagement member 244 at a tip 242 of the reciprocatinganvil adjusting rod 114 and a threaded adjustment member 286 which isdetachably coupled with the anvil control member 120 at a proximal endof the reciprocating anvil adjusting rod 114.

The firing bar 282 is used to stabilize and secure the reciprocatinganvil adjusting rod 114 within the handle 116. Firing bar 282 forms apair of engagement grooves 288 and 290 and has an engagement shaft 292at a distal end of the firing bar 282. Engagement grooves 288 and 290are preferably formed on opposing sides of firing bar 282. Firingtrigger 122 includes an upper end 294 which engages the engagementgrooves 288 and 290 and detachably secures the firing bar 282 and thereciprocating anvil adjusting rod 114 within the cavity 118 of thehandle 116. Alternatively, engagement grooves 288 and 290 may bereplaced with any detachable coupling, as described herein. Preferably,when the firing bar 282 and the reciprocating anvil adjusting rod 114are placed within the cavity 118, portions of the upper end 294 of thefiring trigger 122 each extend into one of the engagement grooves 288and 290, detachably securing both the firing bar 282 and thereciprocating anvil adjusting rod 114 in the cavity 118. By detachablysecuring both the firing bar 282 and the reciprocating anvil adjustingrod 114 in the cavity 118, the engagement grooves 288 and 290 and theupper end 294 of the firing trigger 122 allow for both the firing bar282 and the reciprocating anvil adjusting rod 114 to be easily placedinto and removed from the cavity 118 allowing them to be easily servicedor replaced. The design of the cavity 118 and the features of componentsdescribed above are such that they allow clear visualization by the useras they are placed in the correct location and orientation. Thisarrangement also prevents the user from incorrectly assembling thedevice.

The engagement shaft 292 forms an opening 296 through which the tip 242and the engagement member 244 of the reciprocating anvil adjusting rod114 are received. Receiving the reciprocating anvil adjusting rod 114through the opening 296 of the engagement shaft 292 helps to center thereciprocating anvil adjusting rod 114 within the handle 116 and alignthe reciprocating anvil adjusting rod 114 within the stapling cartridgeassembly 108. The stapling cartridge assembly 108 (see FIGS. 1 and 2)detachably couples with a distal end of the shaft assembly 106 (see FIG.3). The tip 242 of the engagement member 244 of the reciprocating anviladjusting rod 114 extends within and through the casing 110 (see FIG. 2)and detachably couples to the proximal end channel 236 (see FIG. 2) ofthe metal shaft 216 of the anvil assembly 112 using a snap-fit coupling.

Referring to FIG. 3, carrier cover 284 slides over the handle 116 andcovers the firing bar 282 and a portion of the reciprocating anviladjusting rod 114 within cavity 118. Preferably, carrier cover 284 formsan opening 298 through which a threaded portion 132 of the handle 116 isreceived. The opening 298 is preferably U-shaped and formed on anunderside 300 of the carrier cover 284, so that when the carrier cover284 is slid over the handle 116, an abutment portion 302 of the carriercover 284 is pressed against a portion of the handle 116, indicatingthat the carrier cover 284 is properly positioned over the firing bar282 and a portion of the reciprocating anvil adjusting rod 114 withinthe cavity 118. By allowing for carrier cover 284 to slide over thehandle 116, carrier cover 284 protects both the firing bar 282 and thereciprocating anvil adjusting rod 114 within the cavity 118 and allowsfor them to be easily serviced or replaced.

Shaft assembly 106 is detachably coupled with the handle 116 at aproximal end and detachably coupled with the stapling cartridge assembly108 (see FIG. 1) at a distal end. As used herein, the term detachablerefers to a first component or member which is designed to be unfastenedor disconnected without damage to another component or member.Additionally, as used herein, the term detachably coupled or detachablysecured refers to coupling or securing a first member to a second memberin a manner in which the two members are designed to be unfastened ordisconnected from each other without damage to either member. Thisallows for a user to disconnect or unfasten the two members from eachother without damage so that a user may service the two members.Detachable couplings may include a snap-fit coupling, a frictionallyengaging coupling which includes members which frictionally engage eachother, a threaded coupling, a magnetic coupling, or a mechanicalcoupling such as a hook and loop type fastener.

Referring to FIG. 3, preferably the shaft assembly 106 has theconnecting nut 130 with internal threads 304 which are detachablycoupled with the threaded portion 132 on the handle 116. Alternatively,connecting nut 130 may be replaced with any detachable coupling, asdescribed herein. Once detachably coupled with the handle 116, shaftassembly 106 detachably secures the carrier cover 284 to the handle 116allowing for the circular stapling instrument 100, and its components,such as shaft assembly 106, carrier cover 284, handle 116, firing bar282, and the reciprocating anvil adjusting rod 114 to be easilydisassembled and serviced.

By detachably coupling the shaft assembly 106 with the handle 116, bydetachably securing both the firing bar 282 and the reciprocating anviladjusting rod 114 in the cavity 118, by allowing for carrier cover 284to slide over the handle 116, by detachably coupling the reciprocatinganvil adjusting rod 114 with the anvil control member 120, by detachablycoupling the shaft assembly 106 with the handle 116, or by detachablycoupling the anvil assembly 112 (see FIG. 1) with the reciprocatinganvil adjusting rod 114, assembly and disassembly of the circularstapling instrument 100 is made easier and allows for servicing andmaintenance of the various components with the circular staplinginstrument 100.

With reference to FIGS. 15A and 15B, in assembling the circular staplinginstrument 100, the anvil control member 120 is detachably coupled withthe reciprocating anvil adjusting rod 114. Preferably, the anvil controlmember 120 is detachably coupled with the threaded adjustment member 286at a proximal end of the reciprocating anvil adjusting rod 114 byturning the anvil control member 120 on the threaded adjustment member286. Typically, turning the anvil control member counter-clockwise 120opens the device and turning clockwise closes the device.

Then, with reference to FIGS. 16A and 16B, a portion of the anvilcontrol member 120 and a portion of the reciprocating anvil adjustingrod 114 are detachably secured within the cavity 118 of the handle 116.Preferably, the cavity 118 forms an indentation 306 which mates with aportion of the anvil control member 120, in order to detachably securethe anvil control member 120 and the reciprocating anvil adjusting rod114 within the cavity 118. Alternately, the indentation and protrusionrelationship can be reversed. Once the reciprocating anvil adjusting rod114 is placed in the cavity 118 at location 118A, the parallel andplanar walls 114B and 114C (see FIG. 15B) adjoining the cavity 118 areconnected in a fashion that prevents rotational movement of thereciprocating anvil adjusting rod 114 relative to the handle whileallowing longitudinal movement.

With reference to FIGS. 17A, 17B, and 17C, the tip 242 and theengagement member 244 of the reciprocating anvil adjusting rod 114 arereceived through the opening 296 of the engagement shaft 292 of thefiring bar 282 and then the engagement grooves 288, 290 of the firingbar 282 are placed over and then around the upper end 294 of the firingtrigger 122, detachably securing the firing bar 282, the reciprocatinganvil adjusting rod 114, and the anvil control member 120 within thecavity 118.

With reference to FIGS. 18A and 18B, the carrier cover 284 is then slidover the handle 116 and covers the firing bar 282 and a portion of thereciprocating anvil adjusting rod 114 within cavity 118. Preferably, thethreaded portion 132 of the handle 116 is received through the opening298 in the carrier cover 284, and the carrier cover 284 is slid untilabutment portion 302 of the carrier cover 284 is pressed against aportion 132 a of the handle 116, indicating that the carrier cover 284is properly positioned.

With reference to FIGS. 19A, 19B, and 19C, the reciprocating anviladjusting rod 114 is placed through and within the shaft assembly 106and the shaft assembly 106 is detachably coupled with the handle 116.Preferably, shaft assembly 106 has the connecting nut 130 with theinternal threads 304 which are detachably coupled with the threadedportion 132 on the handle 116. The shaft assembly 106 detachably securesthe carrier cover 284 to the handle 116.

Then, with reference to FIG. 2, stapling cartridge assembly 108 isdetachably coupled to the shaft assembly 106, and the tip 242 of thereciprocating anvil adjusting rod 114 extends through a central shaftformed in the stapling cartridge assembly 108. Finally, anvil assembly112 is detachably coupled with the reciprocating anvil adjusting rod 114via the engagement member 244 of the reciprocating anvil adjusting rod114 and the proximal end channel 236 of the metal shaft 216 of the anvilassembly 112.

With reference to FIGS. 20 and 21, in one embodiment, a curved circularstapling instrument 100A is provided which includes a stapling cartridgeassembly 108A having a casing 110A, an anvil assembly 112C attached to acurved reciprocating anvil adjusting rod 114A of an anvil openingmechanism, as discussed above, to prevent accidental removal of theanvil assembly 112C, a curved firing bar 282A which is detachablycoupled with the flexible reciprocating anvil adjusting rod 114A, acarrier cover 284A detachably coupled with a handle 116A, a controlmember 120A detachably coupled with the curved reciprocating anviladjusting rod 114A via a threaded adjustment member 286A, and anergonomic curved shaft assembly 106A having a connecting nut 130Adetachably coupled with the handle 116A via threaded portion 132A.Curved circular stapling instrument 100A includes curved components,such as the flexible reciprocating anvil adjusting rod 114A, the curvedfiring bar 282A, and the curved shaft assembly 106A, to aid in insertioninto a body cavity of a mammal

By having components which are detachably coupled with each othercircular stapling instrument 100 or curved circular stapling instrument100A provide a reusable stapling instrument having an open architecturewhich uses a carrier cover 284, 284A having a u-shaped opening 298, 298Athat allows for additional components, such as reciprocating anviladjusting rod 114, 114A and shaft assembly 106, 106A, to be assembled ina primarily transverse direction. A transverse assembly allows for easyvisualization for assembly and decreases assembly time, improves ease ofassembly, and disassembly. As a result, the amount of time required toassemble the circular stapling instrument 100 or the curved circularstapling instrument 100A having the open assembly architecture is oftenless than one minute. Additionally, the open architecture allows forpresence of features that communicate where the components need to beplaced. Further, by providing components which are detachably coupledwith each other, the circular stapling instrument 100 or 100A is easilyassembled or disassembled, allowing for cleaning and sterilization ofthe circular stapling instrument 100 or 100A after use.

With reference to FIGS. 22-28, in one embodiment, a circular staplinginstrument 100D is provided which includes a stapling cartridge assembly108D having a casing 110D, an anvil assembly 112D attached to areciprocating anvil adjusting rod 114D of an anvil opening mechanism, asdiscussed above, to prevent accidental removal of the anvil assembly112D, a firing bar 282D which is detachably coupled with thereciprocating anvil adjusting rod 114D, a carrier cover 284D coupledwith a handle 116D, a control member 120D coupled with the reciprocatinganvil adjusting rod 114D, and a shaft assembly 106D having a connectingnut 130D coupled with the handle 116D via a threaded portion 132D.Preferably, the circular stapling instrument 100D is a curved circularstapling instrument, as seen with instrument 100D, and includes curvedcomponents, such as a curved reciprocating anvil adjusting rod 114D, acurved firing bar 282D, and an ergonomic curved shaft assembly 106D, toaid in insertion into a body cavity of a mammal However, circularstapling instrument 100D need not be a curved circular staplinginstrument, as seen with circular stapling instrument 100D, and may beany type of circular stapling instrument, such as a relatively straightcircular stapling instrument, as seen with circular stapling instrument100, and have relatively straight components, such as a relativelystraight reciprocating anvil adjusting rod 114D, a relatively straightfiring bar 282D, and a relatively straight shaft assembly 106D.

The reciprocating anvil adjusting rod 114D includes a first engagementmember 244D at a tip 242D of the reciprocating anvil adjusting rod 114Dand a threaded adjustment member 286D at a base 402D of thereciprocating anvil adjusting rod 114D. Preferably, the reciprocatinganvil adjusting rod 114D includes a base 402D at one end, an engagementmember 244D at an opposing end, and a flexible tension band 400D, whichmay be flexible and curved, connecting the base 402D with the engagementmember 244D. With reference to FIGS. 22 and 23, the firing bar 282D ismovably connected at a first end 430D with a firing trigger 122D andmovably connected at a second end 432D with a stapling cartridgeassembly 108D through a second engagement member 416D. With reference toFIG. 28, the firing bar 282D forms a first engagement surface 406D whichfaces a respective second engagement surface 408D formed on thereciprocating anvil adjusting rod 114D. Preferably, the tension band400D forms the second engagement surface 408D which faces the firstengagement surface 406D on the firing bar 282D.

Circular stapling instrument 100D further includes a frictional reducingmember 420D located in between the first and second engagement surfaces406D, 408D in order to reduce friction between the reciprocating anviladjusting rod 114D and the firing bar 282D. Movement between thereciprocating anvil adjusting rod 114D and the firing bar 282D occurswhen the firing trigger 122D is engaged by the handle 116D and fired,causing the firing bar 282D to move towards and engage the staplingcartridge assembly 108D and fire staples from the stapling cartridgeassembly 108D. Movement between the reciprocating anvil adjusting rod114D and the firing bar 282D also occurs when the control member 120D isactivated causing the reciprocating anvil adjusting rod 114D, and theanvil assembly 112D connected to the tip 242D of the reciprocating anviladjusting rod 114D, to move towards or away from the stapling cartridgeassembly 108D in order to adjust a distance between the staplingcartridge assembly 108D and the anvil assembly 112D. Either movementbetween the reciprocating anvil adjusting rod 114D and the firing bar282D causes the reciprocating anvil adjusting rod 114D to slidablyengage the firing bar 282D, and results in friction between thereciprocating anvil adjusting rod 114D and the firing bar 282D. The termslidably engage as used herein refers to movement of one surface over asecond surface while maintaining smooth continuous contact between thetwo surfaces. Friction between the reciprocating anvil adjusting rod114D and the firing bar 282D in curved circular stapling instrument 100Dtypically could be 20-40% higher over a relatively straight circularstapling instrument 100. In one embodiment, the configuration of thecircular stapling instrument 100D, causes the tension band 400D to exerta contact force on the firing bar 282D, increasing friction between thefiring bar 282D and the reciprocating anvil adjusting rod 114D. Byplacing frictional reducing member 420D in between the first and secondengagement surfaces 406D, 408D, friction between the reciprocating anviladjusting rod 114D and the firing bar 282D may be reduced. There alsoexist other areas where frictional forces between the firing bar 282Dand other portions of the handle 116D occur during firing theinstrument. These frictional forces are reduced by providing apredetermined angle on the surfaces in grooves 288D and 290D of thefiring bar 282D. As shown in FIG. 38B, the angled surface 288F can beoriented from 5 degrees to 15 degrees from vertical. This results in a10-20% reduction in force to push the firing bar 282D.

Frictional reducing member 420D may be any mechanical device or chemicalcompound which may be used to reduce friction between two members, suchas between the reciprocating anvil adjusting rod 114D and the firing bar282D. In particular, the frictional reducing member 420D provides areduced coefficient of friction μ_(reduced) between two members which isless than a normal coefficient of friction μ_(normal) present betweenthe two members, when the two members are without the frictionalreducing member. Preferably, the frictional reducing member 420Dprovides for a reduced coefficient of friction μ_(reduced) which is atleast 20% less than, and more preferably, at least 40% less than thenormal coefficient of friction μ_(normal) present between the twomembers.

Chemical compounds for frictional reducing member 420D may include:solid coatings including graphite or polymer coatings such as Teflon.Chemical compounds for frictional reducing member 420D may be applied ascoatings which bond to either or both the first and second engagementsurfaces 406D, 408D. Chemical compounds for frictional reducing member420D may be also be applied as coatings to free moving intermediatecomponents captured between the two engagement surfaces 406D, 408D.Mechanical devices used for frictional reducing member 420D include anymechanical device which can reduce friction between a pair of surfaces,such as a ball bearing or a roller bearing. Frictional reducing member420D may be connected with either or both the reciprocating anviladjusting rod 114D and the firing bar 282D. The frictional reducingmember 402D is designed so that it does not wipe-out or degrade duringcleaning and servicing the handle for reuse.

With reference to FIGS. 25-27, in one embodiment, the frictionalreducing member 420D includes a roller 404D which is connected with thefiring bar 282D using a pin 412D and which is disposed within a cavity410D formed in the firing bar 282D. Preferably, the pin 412D is disposedwithin a hole 414D formed through the firing bar 282D. Preferably, morethan one roller 404D is connected with the firing bar 282D, such asthree rollers 404D. In one embodiment, hole 414D forms a circularopening through which the pin 412D is disposed, as shown in FIG. 26,allowing for little movement of the pin 412D. In one embodiment, thehole 414D forms a generally oval shaped opening through which the pin412D is disposed and may move laterally within, as shown in FIG. 28,allowing for more lateral movement of the pin 412D either towards oraway from either end 430D, 432D of firing bar 282D than top/bottommovement of pin 412D which is not towards or away from either end 430D,432D of firing bar 282D, allowing an additional degree of freedomcompared to the previous embodiment.

FIG. 29 illustrates a perspective view of the annular blade 126 of thestapling cartridge assembly 108 of the circular stapling instrument 100of FIG. 4. As shown in FIG. 29, the annular blade 126 comprises anannular cutting edge 192 and a breakaway washer attachment member 308.The annular blade 126, including the annular cutting edge 192 and thebreakaway washer attachment member 308, is made of a metal such asstainless steel. In other embodiments, the annular blade 126 may be madeof any material hard enough to cut. The breakaway washer attachmentmember 308 comprises a plurality of spaced-apart breakaway washerretention barbs extending from locations 310 of the annular blade 126which are adjacent to the cutting edge 192. The breakaway washerattachment member 308 extends inwardly at a non-parallel angle 312relative to the cutting edge 192. The non-parallel angle 312 may be in arange of 56 to 60 degrees. In other embodiments, the non-parallel angle312 may be in a range of 30 to 60 degrees. In still other embodiments,the breakaway washer attachment member 308 may vary in material,quantity, shape, size, location, direction, or configuration relative tothe annular blade 126. For instance, in other embodiments the breakawaywasher attachment member 308 may comprise a snap, an impression, orother type of attachment member.

FIG. 6 illustrates the anvil base surface 220 of the anvil assembly 112of the stapling reload assembly 102 of the circular stapling instrument100 being in an open position relative to and apart from the casing 110,and the staple driver 156 and the attached annular blade 126 being in apre-fired position retracted within the casing 110. The annularbreakaway washer 214 is press-fit within the cavity 222 of the anvilbase surface 220 of the anvil 210. A protective member 314 is attached,using a hook 316, to a top portion 318 of the annular breakaway washer214 disposed within the cavity 222 of the anvil base surface 220.

FIG. 30 shows a close-up view of the annular breakaway washer 214attached to the protective member 314. The protective member 314comprises an annular protective cap made of a red colored polycarbonate.In other embodiments, the protective member 314 may vary in material,shape, size, location, color, or configuration, and may be attached tothe annular breakaway washer 214 using varying attachment mechanisms. Instill other embodiments, the protective member 314 may not be used andthe annular breakaway washer 214 may be press-fit within the cavity 222of the anvil base surface 220 without the protective member 314.

FIG. 7 shows the anvil base surface 220 of the anvil assembly 112 havingbeen moved to a closed position relative to and adjacent to the casing110 with the staple driver 156 and the attached annular blade 126 stillbeing in the pre-fired position retracted within the casing 110 spacedapart from the annular breakaway washer 214. In this pre-fired positionthe flexible detent members 178 of the staple driver 156 are detachablyconnected to the detent bumps 180 of the casing 110 with the connectionpreventing the staple driver 156 from moving until a pre-determinedamount of force is applied. In other embodiments, the flexible detentmembers 178 and the detent bumps 180 may comprise varying types ofmating members.

FIG. 31 illustrates the staple driver 156 and the attached annular blade126 having been fired moving the staple driver 156 relative to thecasing 110 from the pre-fired position to the fired position in whichthe cutting edge 192 of the annular blade 126 moves into and cuts theannular breakaway washer 214 while the anvil base surface 220 of theanvil assembly 112 is in the closed position. During the firing, theflexible detent members 178 of the staple driver 156 are released fromthe detent bumps 180 of the casing 110 allowing the staple driver 156 tomove past the certain point 320 relative to the casing 110.

FIG. 32 illustrates a close-up view of the cutting edge 192 of theannular blade 126 of FIG. 31 cutting the annular breakaway washer 214.The cutting edge 192 cuts a web 320, disposed between spaced-apart walls322 and 324, of the annular breakaway washer 214. As this occurs, thebreakaway washer attachment member 308 fixedly attaches to one of thespaced-apart walls 322 of the annular breakaway washer 214 locking theannular blade 126 to the annular breakaway washer 214 with theprotective member 314 (see FIG. 31) still attached to the top portion318 (see FIG. 31) of the annular breakaway washer 214 disposed withinthe cavity 222 of the anvil base surface 220.

FIG. 33 illustrates the anvil base surface 220 of the anvil assembly 112having been moved back into the open position away from the casing 110after the staple driver 156 and the attached annular blade 126 werefired cutting the annular breakaway washer 214. The annular breakawaywasher 214 remains locked in place over the annular blade 126, due tothe annular breakaway washer attachment member 308, with the protectivemember 314 still attached to the top portion 318 of the annularbreakaway washer 214 acting as a protective barrier over the cuttingedge 192 of the annular blade 126. The protective member 314 preventsthe cutting edge 192 of the annular blade 126 from making an unintendedcut after the annular blade 126 has been fired. At least one of theannular breakaway washer 214 or the protective member 314 comprises avisual indicator 326 indicating, as a precautionary measure, that thestaple driver 156 and the attached annular blade 126 have been fired.The visual indicator 326 comprises a first color which is different thana second color of the casing 110 of the circular stapling apparatus 100.In other embodiments, the visual indicator 326 may comprise any type ofvisual indicator visually indicating when the staple driver 156 and theattached annular blade 126 have been fired. In another embodiment, onlythe inner portion of the cut annular breakaway washer 214 and the visualindicator 326 remain attached to the annular blade 126. The outerportion of the cut annular breakaway washer 214 remains attached to theanvil base surface 220 after opening the instrument.

FIG. 34 shows the anvil 210 of the anvil assembly 112 of FIG. 33 havingbeen removed from the circular stapling instrument 100, after the stapledriver 156 and the attached annular blade 126 were fired cutting theannular breakaway washer 214, with the annular breakaway washer 214 andprotective member 314 remaining behind attached to the annular blade 126due to the washer attachment member 308. The protective member 314continues to prevent the cutting edge 192 of the annular blade 126 frommaking an unintended cut after the staple driver 156 and the attachedannular blade 126 have been fired. Moreover, the visual indicator 326continues to indicate that the staple driver 156 and the attachedannular blade 126 have been fired.

FIG. 35 illustrates a new anvil 210C having attempted to be attached tothe circular stapling instrument 100 of FIG. 34. As shown in FIG. 36,the protective member 314, attached to the annular breakaway washer 214which is attached to the fired annular blade 126, interferes with thenew anvil 210C from being attached to the circular stapling instrument100. As shown in FIG. 35, this is due to the diameter 328 of theprotective member 314 being greater than an inner diameter 330 of thenew annular breakaway washer 332. Even if the protective member 314 wasnot attached to the annular breakaway washer 214, the annular breakawaywasher 214 would still interfere with the new anvil 210C from beingattached to the circular stapling instrument 100 as a result of theannular breakaway washer 214 having the same or larger diameter 334 asthe inner diameter 330 of the new annular breakaway washer 332.

In order to use the circular stapling instrument 100 of FIG. 34 again,the stapling reload assembly 102 shown in FIGS. 1-2 may be removed fromthe circular stapling instrument 100 thereby removing the fired annularblade 126 and the attached breakaway washer 214. After sterilizing theun-removed portion (such as handle 116 and other un-removed componentsof FIG. 1) of the circular stapling instrument 100, another unusedstapling reload assembly, comprising another unused annular blade andanother unused breakaway washer, may be attached to the sterilizedun-removed portion of the circular stapling instrument 100 prior tousing the circular stapling instrument 100 again. FIG. 37 illustrates aflowchart of one embodiment of a method 340 of locking a blade to abreakaway washer of a circular stapling instrument. In step 342, acircular stapling instrument is provided. The provided circular staplinginstrument comprises a casing, a staple driver, an anvil assembly, and ablade. The staple driver is moveably disposed within the casing. Theanvil assembly comprises a breakaway washer attached to an anvil basesurface. The blade is attached to the staple driver.

In step 344, the anvil assembly is moved from an open position away fromthe casing to a closed position adjacent to the casing. In step 346, thestaple driver is moved from a pre-fired position, in which the blade hasnot cut the breakaway washer and in which a breakaway washer attachmentmember of the blade has not attached to the breakaway washer, to a firedposition in which the blade cuts the breakaway washer and the breakawaywasher attachment member of the blade fixedly attaches to the breakawaywasher. The breakaway washer attachment member may comprise at least onebreakaway washer retention barb extending from the blade at anon-parallel angle to a cutting edge of the blade. The non-parallelangle may be in a range of 56 to 60 degrees. In other embodiments, thenon-parallel angle may be in a range of 30 to 60 degrees. In still otherembodiments, the breakaway washer attachment member may vary. In oneembodiment, step 346 may comprise the blade cutting a web of thebreakaway washer, and the at least one breakaway washer retention barbfixedly attaching to one of spaced-apart walls of the breakaway washer.

In optional step 348, one or more of the following may occur: thebreakaway washer may interfere with one or more components of thecircular stapling instrument to prevent the blade from being retractedinto the casing to be used again; the breakaway washer, or a protectivemember attached to the breakaway washer, may act as a protective barrierover the blade; or a visual indicator of the breakaway washer, or ofanother member attached to the breakaway washer, may visually indicatethat the staple driver has been fired.

In optional step 350, the following steps may be followed: a staplingreload assembly may be removed from the circular stapling instrumentthereby removing the used blade and the breakaway washer; an un-removedportion of the circular stapling instrument may be sterilized; and anunused stapling reload assembly may be attached to the circular staplinginstrument, comprising an unused blade and an unused breakaway washer,prior to using the circular stapling instrument again. In otherembodiments, one or more steps of the method 340 may be varied.

One or more embodiments of the disclosure may result in any of thefollowing: the prevention of a used blade of a fired circular staplinginstrument from being inadvertently used again in another procedurethereby improving cleanliness and safety; the prevention of a used bladeof a fired circular stapling instrument from making an unintended cut;the prevention of the misfiring of a circular stapling instrument; oranother type of benefit.

FIGS. 38-46 illustrate various views of the circular stapling instrument100 of the embodiment of FIGS. 1 and 2 showing a locking mechanism 352,in various states, that may be used with any embodiments of thedisclosure to prevent misfiring of the firing trigger 122 andcorresponding staple driver 156. FIGS. 38-40 illustrate various views ofthe anvil assembly 112 disposed in an open position, out of a firingzone, away from the casing 110 with the firing trigger 122 and theindirectly affected staple driver 156 in a locked state in pre-firedpositions. When the anvil assembly 112 is disposed in the open position,out of the firing zone, away from the casing 110, using the attachedreciprocating anvil adjusting rod 114 and anvil control member 120, theanvil base surface 220 is disposed at a distance 354 in a range of 0.100to 3.0 inches away from the end of the staple guide 148. In thispre-fired position, a threaded end 286 of the reciprocating anviladjusting rod 114 is disposed at and within an inner portion 358 of themating threaded shaft 360 of the anvil control member 120, and isdisposed apart from end 362 of the mating threaded shaft 360 of theanvil control member 120.

A ledge 364 of the firing trigger 122 is abutted against a first portion366 of the reciprocating anvil adjusting rod 114 which acts as thelocking mechanism 352 and blocks and prevents the firing trigger 122from rotating in direction 124. A second portion 370 of thereciprocating anvil adjusting rod 114 is disposed apart from the ledge364. The ledge 364 comprises opposed walls 372 and 374 which aredisposed a distance 376 of 0.190 inches apart. The width 378 of thefirst portion 366 of the reciprocating anvil adjusting rod 114 is 0.290inches. The width 380 (see FIG. 43) of the second portion 370 of thereciprocating anvil adjusting rod 114 is 0.170 inches. The firingtrigger 122 is prevented from rotating in direction 124 due to the width378 of the first portion 366 being greater than the distance 376 betweenthe opposed walls 372 and 374 of the ledge 364.

The upper end 294 of the firing trigger 122 is mated in engagementgrooves 288 and 290 (see FIG. 3) of the firing bar 282. The upper end294 of the firing trigger 122 comprises opposed surfaces 294A and 294Bwhich are disposed a distance 382 of 0.574 inches apart. The distance382 between the opposed surfaces 294A and 294B is greater than the width378 of the first portion 366 allowing the opposed surfaces 294A and 294Bto pass over the first portion 366 into the engagement grooves 288 and290. End 384 of the firing bar 282 is disposed apart from an end 386 ofthe staple driver 156. As a result of the first portion 366 of thereciprocating anvil adjusting rod 114 blocking the firing trigger 122from rotating in direction 124, the end 384 of the firing bar 282, whichis mated to the firing trigger 122, remains in a position disposed apartfrom the end 386 of the staple driver 156 keeping the staple driver 156in the pre-fired, locked state.

FIGS. 41-43 illustrate various views of the anvil assembly 112 disposedin a closed position, in the firing zone, adjacent the casing 110 withthe firing trigger 122 and the indirectly affected staple driver 156 inan unlocked state ready to fire but still in their same pre-firedpositions as shown in FIGS. 38-40. When the anvil assembly 112 isdisposed in the closed position in the firing zone adjacent the casing110, using the attached reciprocating anvil adjusting rod 114 and anvilcontrol member 120, the anvil base surface 220 is disposed at a distance388 in a range of 0.06 to 0.100 inches away from the end of the stapleguide 148. The anvil control member 120 has been rotated causing thethreaded end 286 of the reciprocating anvil adjusting rod 114 to move indirection 390 away from the inner portion 358 of the mating threadedshaft 360 of the anvil control member 120 towards and to the end 362 ofthe mating threaded shaft 360 of the anvil control member 120. As aresult of this movement, the first portion 366 of the reciprocatinganvil adjusting rod 114 has been moved in direction 390 to be disposedapart from the opposed walls 372 and 374 of the ledge 364 so that thefirst portion 366 no longer interferes with the ledge 364. The secondportion 370 of the reciprocating anvil adjusting rod 114 has also beenmoved in direction 390 from a position apart from the ledge 364 to aposition disposed over the ledge 364.

Due to the width 380 of the second portion 370 being less than thedistance 376 between the opposed walls 372 and 374 of the ledge 364, thefiring trigger 122 may now be freely fired without abutting against theadjacent second portion 370. The opposed surfaces 294A and 294B of theupper end 294 of the firing trigger 122 are still mated in theengagement grooves 288 and 290 (see FIG. 3) of the firing bar 282.Because the firing trigger 122 has not been rotated in direction 124and, although unlocked, is still in the pre-fired position, the firingtrigger 122 has not moved the mating firing bar 282 and the end 384 ofthe firing bar 282 is still disposed apart from the end 386 of thestaple driver 156 leaving the staple driver 156 in its unfired position,but ready to be fired.

FIGS. 44-46 illustrate various views of the anvil assembly 112 disposedin the closed position, in the firing range, adjacent the casing 110with the firing trigger 122 having been rotated in direction 124 firingthe firing trigger 122 and the indirectly affected staple driver 156.The firing trigger 122 was allowed to fire because the first portion 366of the reciprocating anvil adjusting rod 114 was previously moved indirection 390 to be disposed apart from the ledge 364 so that the firstportion 366 no longer interfered with the ledge 364, and the width 380of the second portion 370 of the reciprocating anvil adjusting rod 114is less than the distance 376 between the opposed walls 372 and 374 ofthe ledge 364 which allowed the firing trigger 122 to be fired withoutinterference from the second portion 370.

During the firing of the firing trigger 122, as the firing trigger 122was rotated in direction 124, the opposed surfaces 294A and 294B of theupper end 294 of the firing trigger 122 moved in direction 392 abuttingagainst the respective mated engagement grooves 288 and 290 (see FIG. 3)of the firing bar 282 forcing the firing bar 282 to also move indirection 392. This movement forced the end 384 of the firing bar 282against the end 386 of the staple driver 156 forcing the staple driver156 to also fire and move in direction 392. During this firing of thestaple driver 156, the movement of the staple driver 156 ejects staples104 (see FIGS. 7 and 31) out of the annular staple holder 148 (see FIGS.4-5, 7, and 31) and cuts tissue with the annular blade 126 (see FIG. 31)attached to the staple driver 156 as previously discussed.

In such manner, the locking mechanism 352 automatically preventsmisfiring of the firing trigger 122 and corresponding staple driver 156and staples staples 104 (see FIGS. 7 and 31) without a user of thecircular stapling instrument 100 having to manually implement a lockingmechanism. Moreover, the locking mechanism 352 automatically locks thefiring trigger 122 and corresponding staple driver 156 and staples 104(see FIGS. 7 and 31) in the pre-fired position whenever the anvilassembly 112 is in the open position, and automatically unlocks thefiring trigger 122 and corresponding staple driver 156 and staples 104(see FIGS. 7 and 31) whenever the anvil assembly 112 is in the closedposition. The locking mechanism 352 works in this manner regardless ofthe number of times the anvil assembly 112 has been opened and closed,and regardless of whether the firing trigger 122 and correspondingstaple driver 156 and staples 104 (see FIGS. 7 and 31) have been fired.

FIG. 47A shows another embodiment of the circular stapling instrument ofFIG. 1 having another locking mechanism 352A that prevents movement ofthe staple driver 156 when the stapling reload assembly 108 (see FIG. 2)is assembled to the handle 116 (see FIG. 2) and the anvil 210 is in theopen position. In this condition with the anvil 210 in the openposition, the portion 114E of the reciprocating anvil adjusting rod 114adjacent to the flexible detent members 178 has a size, width, ordiameter 401 (see FIG. 3B) which is smaller than but close enough insize to the width or diameter 196A of the hole 196 of the annularinterior shaft 194 of the staple driver 156 preventing the flexibledetent members 178 from having enough distance 400, between the portion114E of the anvil adjusting rod 114 and the inner hole surface 196B, todeflect and disengage from the detent bumps 180, thereby in turnpreventing movement and firing of the staple driver 156. As shown inFIG. 47B, when the anvil 210 is near the closed position the narrowerportion 114F of the reciprocating anvil adjusting rod 114 adjacent tothe flexible detent members 178 has a size, width, or diameter 402 (seeFIG. 3A) which is smaller enough in size than the width or diameter 196Aof the hole 196 of the annular interior shaft 194 of the staple driver156 to allow the flexible detent members 178 to have enough distance400, between the portion 114F of the anvil adjusting rod 114 and theinner hole surface 196B, to deflect and disengage from the detent bumps180, thereby in turn allowing movement and firing of the staple driver156.

The abstract of the disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing detailed description, it can be seen that various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed embodiment. Thus the following claims arehereby incorporated into the detailed description, with each claimstanding on its own as a separately claimed subject matter. Whilevarious embodiments of the disclosure have been described, it will beapparent to those of ordinary skill in the art that other embodimentsand implementations are possible within the scope of the disclosure.Accordingly, the disclosure is not to be restricted except in light ofthe attached claims and their equivalents.

1. A circular stapling instrument comprising: a reciprocating driveshaft having a first engagement member at a tip of the reciprocatingdrive shaft and a threaded adjustment member at a base of thereciprocating drive shaft; a firing bar movably connected at a first endwith a firing trigger and movably connected at a second end with astapling head assembly through a second engagement member, wherein thefiring bar forms a first engagement surface which faces a respectivesecond engagement surface formed on the reciprocating drive shaft; and africtional reducing member located in between the first and secondengagement surfaces in order to reduce friction between thereciprocating drive shaft and the firing bar.
 2. The circular staplinginstrument of claim 1, wherein the reciprocating drive shaft and thefiring bar are both curved.
 3. The circular stapling instrument of claim2, wherein the reciprocating drive shaft includes a base at one end, anengagement member at an opposing end, and a tension band connecting thebase with the engagement member.
 4. The circular stapling instrument ofclaim 3, wherein the tension band forms the second engagement surfacewhich faces the first engagement surface on the firing bar.
 5. Thecircular stapling instrument of claim 4, wherein the tension band exertsa contact force on the firing bar, increasing friction between thefiring bar and the reciprocating drive shaft.
 6. The circular staplinginstrument of claim 1, wherein the frictional reducing member isconnected with the firing bar.
 7. The circular stapling instrument ofclaim 6, wherein the frictional reducing member is one of a mechanicaldevice or a chemical compound for reducing friction between two members.8. The circular stapling instrument of claim 6, wherein the frictionalreducing member is one of a roller or a ball bearing.
 9. The circularstapling instrument of claim 1 further comprising an anvil assembly, andwherein the tip of the engagement member of the reciprocating driveshaft engages the anvil assembly.
 10. A circular stapling instrumentcomprising: a reciprocating drive shaft for adjusting a distance betweenan anvil assembly and a stapling head assembly; a firing bar forengaging and activating the stapling head assembly to release staples,wherein the firing bar forms a first engagement surface which faces arespective second engagement surface formed on the reciprocating driveshaft; and a frictional reducing member located in between the first andsecond engagement surfaces in order to reduce friction between thereciprocating drive shaft and the firing bar.
 11. The circular staplinginstrument of claim 10, wherein the reciprocating drive shaft has afirst engagement member at a tip of the reciprocating drive shaft and anadjustment member at a base of the reciprocating drive shaft
 12. Thecircular stapling instrument of claim 10, wherein the firing bar ismovably connected at a first end with a firing trigger and movablyconnected at a second end with the stapling head assembly through asecond engagement member.
 13. The circular stapling instrument of claim10, wherein the firing bar is curved.
 14. The circular staplinginstrument of claim 13, wherein the reciprocating drive shaft includes abase at one end, an engagement member at an opposing end, and a tensionband connecting the base with the engagement member.
 15. The circularstapling instrument of claim 14, wherein the tension band forms thesecond engagement surface which faces the first engagement surface onthe firing bar.
 16. A circular stapling instrument comprising: areciprocating drive shaft which slidably engages a firing bar, whereinthe firing bar forms a first engagement surface which faces a respectivesecond engagement surface formed on the reciprocating drive shaft; and africtional reducing member located in between the first and secondengagement surfaces in order to reduce friction between thereciprocating drive shaft and the firing bar.
 17. The circular staplinginstrument of claim 16, wherein the frictional reducing member isconnected with the firing bar.
 18. The circular stapling instrument ofclaim 17, wherein the frictional reducing member is one of a mechanicaldevice or a chemical compound for reducing friction between two members.19. The circular stapling instrument of claim 17, wherein the frictionalreducing member is one of a roller or a ball bearing.
 20. The circularstapling instrument of claim 16 further comprising an anvil assembly,and wherein a tip of an engagement member of the reciprocating driveshaft engages the anvil assembly.